The present invention relates to apparatus and methods for joining fabrics and, more particularly, to apparatus and methods for joining fabrics without sewing.
Garments have traditionally been produced by a cut-and-sew technique in which a plurality of separate fabric pieces are joined together, typically by sewing with thread, to form the finished garment. The drawbacks of this method of production are well known, and thus efforts have been made to devise alternative methods of production that can reduce or eliminate the amount of sewing required for assembling a garment. Major strides in this direction have been made, at least for certain types of garments, by applying circular knitting techniques to produce the main tubular body of the garment without seams. In general, however, it is still necessary to finish the garment by sewing, such as for applying decorative or elastic trim or banding around leg openings, neck openings, arm openings, waist openings, or the like, and for joining different portions of the garment that cannot be integrally knit together during the circular knitting process. For example, a so-called xe2x80x9cseamlessxe2x80x9d panty still requires at least one seam, typically located in a crotch region of the panty, for joining together a front panel and a back panel of the tubular fabric blank from which the panty is made.
The formation of such seams and the attachment of elements such as elastic are to this day still performed by sewing with thread in the commercial production of most garments. This generally requires the manufacturer to keep an extensive inventory of dye-to-match sewing thread so that the thread will be the same color as the fabric of the garment. It would be desirable to eliminate the requirement of sewing with thread to assemble and finish a garment.
U.S. Pat. No. 5,820,443 issued to Burr discloses a brassiere having two side parts each defining a cup joined together in a front central area by a thermally produced weld, in particular a weld formed by ultrasonic welding. Each. Ride part includes a blank covering the entire surface of the side part and composed at least in part of thermoplastically fusible fibers. Frame-like reinforcement parts also composed of thermoplastically fusible fibers are ultrasonically welded to the blank parts at least along their outer edges. Back fasteners and shoulder straps are attached to the side parts by ultrasonic welding. The patent schematically illustrates an apparatus for forming the welded joint between the two side parts in the front central area. The apparatus consists of a bottom abutment on which the material to be joined is supported, and a sonotrode that is lowered into engagement with the material to compress and weld the material, similar to a pressing operation. It will be appreciated that such an apparatus would be of limited usefulness in the general assembly of garments of various types, because many garments require long seams between parts for which the pressing type of operation described in the Burr patent would be inefficient and cumbersome.
The present invention enables a wide variety of garments to be assembled without sewing. The apparatus and method of the invention can join components of a garment with seams that are as strong as or stronger than conventional stitched seams, and the seams can be made faster than conventional sewing. The apparatus is also safer and much quieter than a conventional sewing machine, thus providing a better work environment. Moreover, unlike a joint made by conventional sewing with thread, the joint made in accordance with the invention does not limit the degree of stretch of the fabric, which is beneficial in some applications. To these ends, an apparatus is provided for joining together two or more fabric components without thread, the components including at least one ultrasonically bondable component. The apparatus comprises an ultrasonic horn operable to emit ultrasonic energy through a fabric-engaging end face thereof, and a movable anvil support having an outer peripheral fabric-engaging surface that defines one or more anvil structures for focusing ultrasonic energy emitted by the horn. The anvil structure(s) and the horn are arranged so as to define a nip between the respective fabric-engaging surfaces thereof for receiving the components to be joined. The movable anvil support rotates about an axis thereof as the components pass through the nip such that the anvil structures are stationary relative to the components passing through the nip. The horn emits ultrasonic energy and the one or more anvil structures focus the ultrasonic energy on one or more regions of the at least one ultrasonically bondable component in the nip so as to locally heat and bond the one or more regions. Thus, the apparatus of the invention enables even very long continuous seams to be made in an efficient manner.
Preferably, the apparatus includes a drive system for engaging the components and moving the components through the nip. Advantageously, the anvil support is a wheel or disk-shaped member that is rotatably driven and comprises part of the drive system, rotation of the anvil support causing the components to be moved through the nip. One or more anvil structures are formed on the outer peripheral surface of the wheel. The drive system preferably includes a main drive motor coupled with the wheel for rotatably driving the wheel. Alternatively, the wheel could be freewheeling, and the fabric components could be moved through the nip in another fashion.
In one preferred embodiment of the invention, the apparatus is adapted for attaching a strip of ultrasonically bondable trim along an edge of a fabric component by folding the trim over the edge of the component and bonding the trim thereto. The trim can be, for example, an elastic banding or a decorative trim. To this end, the apparatus includes a feed assembly for folding the trim and feeding the folded trim into the nip between the horn and the anvil wheel. The feed assembly preferably includes a feed motor for rotatably driving a feed roll that engages the trim so as to advance the trim from a trim supply toward the nip. A controller coordinates operation of the main drive motor for the anvil wheel and the feed motor for the trim such that the trim is advanced at a rate substantially matching the speed of the outer peripheral surface of the anvil wheel.
The anvil structures on the periphery of the anvil wheel can be designed to impart various patterned appearances to the fabric components being joined. As one example, the anvil structures can be configured to impart an appearance of conventional stitching to the fabric. This can be accomplished by providing protrusions on the anvil wheel regularly spaced about its circumference to impart the appearance of holes formed by a needle in conventional sewing. Various styles of stitching can be simulated. Alternatively, the anvil structure can be continuous rather than discontinuous, so as to form a continuous bond line along the fabric as the fabric passes through the nip of the apparatus.
The invention thus offers several benefits. The seams produced by the apparatus can be made faster than is typically possible with conventional sewing machines, the seams can be as strong as or stronger than stitched seams, and the seams do not limit the stretch of the fabric as stitched seams typically do. There is no need to keep an inventory of dye-to-match sewing thread. The apparatus has few moving parts and thus is much quieter than a conventional sewing machine. Needles and their associated hazards are eliminated and, as an ancillary benefit of the improved safety of the apparatus, new operators can be more easily trained because there is no need to overcome their initial fear as is often the case with conventional sewing machines.